[maikhoepfel]

For your #2, quoting from the link:

Loads and stores are relative to the X, Y, and Z registers, which are aliases for the 16 bit register pairs starting at r26, r28, and r30 respectively (r30 is an alias for Z)

[raphman]

Indeed. However, this explanation is only given after the example has already made use of these registers. As I stated, just a very minor issue... :)